Electric furnace.



No. 688,861. Patented Deb. I7, lam.

c.- A. KELLER.

ELECTRIC FURNACE.

(Application filed Dec. 3, 1900.)

3- ShabtsSheel 2.

(No Model.)

No. 688,86l. Patented Dec. l 7, l90l.

C. A; KELLER. ELECTRIC FURNACE.

(Application filed Dec. 3. 1900.)

(No Model.) 3 Sheets-Sheet 3,

' UNITED STATES PATENT OE IcE.

CHARLES ALBERT KELLER, OF PARIS, FRANCE.

ELECTRIC FURNACE.

SPECIFICATION forming part of Letters Patent No. 688,861, dated. December 17, 1901. Application filed December S, 1900. Serial No. 38,496. (No model.)

To aZZ whom it may concern:

Be it known that 1, CHARLES ALBERT KEL- LER, a citizen'of the Republic of France,'residing in Paris, France, have invented certain new and useful Improvementsin Electric Furnaces, Embodied in an Electric Furnace with Two Movable Electrode-Carriages, of which thefollowing is a specification.

My invention relates to improvements in electric furnaces; and the object of these improvements is to obviate the inconveniences inherent to the said furnaces as they-were used heretofore.

In order to make my invention well understood, it is necessary to shortly review the arrangement of the electric furnaces as they are now in use. In most of these furnaces one or more movable electrodes placed in a vertical, horizontal, or slanting position are used in such a way that part of them is outside and part inside the furnace. The end of that part of the electrode which is inside the furnace is either immersed in the matter infusion or immediately above. As a consequence of this arrangement the part of the electrode inside the furnace reaches a very high temperature, and this high temperature is communicated by the calorificconductibility to the part of the electrode outside the furnace to an extent sufficient to produce a slow combustion of this part of the electrode through its contact with the oxygen of the.

air. This combustion causes a rapid enfeeblement of the said section of the electrode, so that the latter breaks at this placewhen only twenty or thirty per cent. of its full length has been used; but there is still another inconvenience, at least with those furnaces where the movable electrodes are placed vertically-nainely, the working of the furnace has to be interrupted as soon as the mass to be treated reaches a certain level, for otherwise the furnace might be damaged in its u p? per part it it is a covered furnace, and at any rate the mass already treated would on account of the height of its level cause a loss of energy resulting from the introduction of its ohmic resistance into the electric circuit.

Moreover, when the movable vertical elec-' trode becomes rather short by its being burned up to such apoint the metallic pieces serving for the fastenings and connections are side the furnace, the electrodes being held by two movable sockets, wherein the fastenings and connections are arranged so that they are kept separate from the seat of the heat, so that they cannot be reached by the deteriorating action of the latter.

The furnace shown in the accompanying drawings embodies my invention.

Figure 1 isa longitudinal section of the said furnace. Fig. 2 is a plan view of the same as it is represented in Fig. 1. Fig. 3 is a cross-section of the same on the line A B of Fig. 1. Fig. lisa longitudinal section of one of the movable electrode carriers or sockets, and Fig. 5 is a plan view of the latter.

The floor of the furnace is formed of two equalcarriages bearing the electrodes, Fig. 1. The latter consist of a certain number of carbon blocks Z, preferably of a square section, which are placed on the metallic bottom of the carriage, whose upper part is formed of a vaulted ceiling provided with apertures of the same section as the carbon blocks, whose heads project a suitable distance through said apertures in the upper part of the carriage. The said ceiling of the carriage is formed of two arches a a, made of. refractory bricks, the arches leaning on one side against a metallic central piece 19 of suitable form and on the other side against the walls 0 c. A filling of refractory material (represented at to) may be employed to levelthe tops of the arches. On the emerging heads of the carbon blocks Zare placed the small carbon sticks (1 without any fastenings. In this way the electric contacts are completely separated from the fusion-hearth, and the calorific conductibility of the parts separating them therefrom is reduced to a minimum, so that those contacts are kept at the lowest temperature which it is possible to obtain for them. To the bottom and the sides of the lower parts of the carbon blocks l l are fastened in any suitable manner thin copper electric machine. The pieces by which the copper bars are fastened to the carbon blocks are arranged so that they can be made iute' gral with the bottom of the carriage, so that the carbon blocksl l are integral on one hand with the copper bars 6 e conducting on the current and with the bottom of the carriage on the other.

The two carriages bearing the electrodes may, if this should he deemed necessary, be separated by a single central fusion-hearth h, the size of which would have to be varied according to the electric power to be used. This hearth would be made of bricks and would have no other purpose than to support the matter to be treated. Both carriages have metallic parts g by which they engage the cavities i i, provided in the hearth 7L, in order to prevent the couductingbodies, as well as the mass in fusion, from dropping from the carriage. The fusion-hearth h is mounted on wheels which run upon rails located perpendicularly to those which sustain the electrode-carriages. (See Figs. 1 and 3.) The two carriages are connected with each other by a system of cables 92 n and pulleys it It, one of which has a crank o with a handle. In order to render the control of the cable still more secure,one could replace the controlling pulley by a drum and wind the cable twice or thrice around this drum.

The upper part of the furnace is terminated by a refractory vault p, bearing a chimney 1", allowing of the evacuation of the hot gases. Apertures s s are provided in the walls of the furnace in order to permit the electrode-carriages to be introduced into the furnace, whereafter the said apertures may be closed or not, as the case may be.

The working of the furnace is as follows: The two electrode-carriages being placed in the circuit between the two conductors of the dynamo-electric machine, as soon as the latter starts its work the current passes into the carbon blocks Z l, which transmit the same to the small electrodes (1 (:1. Good care must be taken before starting the Work that the two carriages, as Well as the space between them, be covered with carbon or any other conducting material, which when the current passes therethrough is brought to a very high degree of incandescence. This is indicated at 'y. The second carriage makes the circuit and acts from an electrical standpoint exactly in the same way as the first onethat is to say, the electric current runs through the small electrodes 01 d and the carbon blocks 1 Z, from whence it returns to the dynamo. By the imperfect contact between the small electrodes and the solid carbon blocks small electric arcs areproduced at the junction of the same, and as the matter to be treated will not fail to be filtered through the layer covering the elecbe treated is introduced into the furnace through the openings t t, and a third opening "1/- maybe provided in order to serve as an on tlet for the finished or treated mass. The regulation of the resistance is obtained by a simultaneous displacement of the two electrodecarriages, this displacement being obtained by means of turning the crank 0 in the direction required and according to the degree of resistance which it is desirable to obtain. If the crank is turned in the direction of the arrow a, the two carriages will run apart under the action of the cables, and if the crank is to rn ed in the other direction the two carriages will approach each other. WVhen the two carriages are drawn apart, this displacement will cause a break in the mass under treatment at the junctions of the two carriages with the central hearth, so that the break takes place in the zone of the greatest heat and where the mass under treatm ent has reached the highest degree of fusion. Therefore this point is also the best place for collecting or evacuating the mass finished to be treated. It follows that such a disposition of the furnace is the best for purposes of electrometallurgy, for it permits by theincandescence of the matter placed between the two junctions just spoken of of regulating the temperature which is then dependent on the electric currents employed. A special advantage of this arrangement is thatit permits of avoiding the volatilization of matter whose temperature of fusion is not high. Moreover, the perturbations so detrimental in certain metallurgic processes and yet unavoidable with the ordinary furnaces on account of the presence of electrodes of carbon are also avoided with my furnace, as the matter under treatment is not brought into contact with the extremities of the carbons of the movable electrode hearings or carriages. In order to obtain this result, it would only be necessary, but also sufficient, to place on the upper extremities of the carbons of the carriages a conducting-body not susceptible of modifyingindustrially the composition of the matter to be treated. In this way the detrimental action spoken of above, and which consists in the carburization of the mass to be obtained, is sure to be avoided.

\Vhenever the metal or alloy to be obtained should not be carburized, it is clear that the layer y, serving to insure the passage of the current at the beginning of the operation, should not be of carbon, but of a conductor not susceptible of modifying industrially the composition of the material to be obtained, and this conductor will preferably be of the same material as that-desired to be obtained or of a material that enters into the composition of this last. If, for example, it is desired to obtain chrome-iron, and this not to be carburized, the upper extremities of the car bons d of one of the movable carriages will be united with those of the other by a layer of particles of iron covering also the central hearth, and in any case the purpose of this layer,

too

whatever may be its composition, remains the same. i The electrical connection is closed in beginning the operation through the layer y. When the conducting-body is brought to a sufficient temperature by the passage of the current, it is then that the furnace is charged with the material to be treated. The introduction of this material is made through the upper orifices t t and the side orifice t. The material is spread upon the carriages the same as the layer y. The withdrawal is through the spout v.

When the small electrodes are burned up,

it is only necessary in order to replace them.

parts d, suffer almostno deteriorationwhatever and are used up very slowly, and as they are of very small dimensions it is possi bleto use for this purpose the non-utilized break and waste of electrodes cast ofi by other branchesofindustry-forinstance,thebroken carbon sticks of arc-lampswhereby an important result of economy is to be obtained in all manufacturing branches using electric furnaces. It will be well to mention that this system permits of preserving the big electrodes andof replacing only the smaller ones,

- for when the mass treated is taken away from the electrodecarriage the small electrodes only are bound up with the mass founded when the latter has cooled. The electrodes instead of occupying the top of the carbon blocks, as shown by the drawings, could as well as these carbon blocks be placedon any other geometrical linefor instance, on a straight line parallel to the junctions ofthe carriages.

As the two movable electrode-carriages do not require any openings in the furnace for the passage of the electrodes, as is necessary with the ordinary furnaces, my system permits of a complete closing of the electric furnace in all cases where it is desirable or necessary to exclude the air from operation or to operate under pressure.

It must be well understood that the furnace shown is only intended as one development of the inventionand that the latter may be carried out in another form according to the different applications the furnace may be called upon to serve.

What I claim as my invention, and desire to secure by Letters Patent, is-

1. An electric furnace comprising a fusionhearth h provided with cavities 7;, two electrodes inclined toward-the fusion-hearth provided each with a tongue 9 entering one of the said cavities 2', these electrodes being mounted on wheels running upon rails, and connected by means of cables n n bearing upon return-pulleys 70 lo and passing around a drum m provided with a hand-crank 0, the said fusion-hearth h being likewise mounted on wheels running upon rails disposed perpendicularly to the said rails of the said electrodes, substantially as shown and described.

2. An electric furnace comprising two electrodes mounted by means of wheels upon rails and united by means of cables bearing upon return-pulleys 7t 7t and passing around a drum on provided with a hand-crank 0, each of these electrodes being composed of a carriage divided by means of small arches a in two parts of which the lower one is cooled by. 

